StoreManagerTrait.h

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#ifndef UtilAlgos_StoreManagerTrait_h
#define UtilAlgos_StoreManagerTrait_h
/* \class helper::CollectionStoreManager
 *
 * \author: Luca Lista, INFN
 *
 */
#include "DataFormats/Common/interface/OwnVector.h"
#include "DataFormats/Common/interface/RefVector.h"
#include "DataFormats/Common/interface/RefToBase.h"
#include "DataFormats/Common/interface/RefToBaseVector.h"
#include "DataFormats/Common/interface/Ptr.h"
#include "DataFormats/Common/interface/PtrVector.h"
#include "FWCore/Framework/interface/Event.h"
#include <memory>
#include "boost/type_traits.hpp"

namespace helper {

  template <typename Collection>
  struct IteratorToObjectConverter {
    typedef typename Collection::value_type value_type;
    template <typename I>
    static value_type convert(const I &i) {
      return value_type(**i);
    }
  };

  template <typename T>
  struct IteratorToObjectConverter<edm::OwnVector<T> > {
    typedef std::unique_ptr<T> value_type;
    template <typename I>
    static value_type convert(const I &i) {
      return value_type((*i)->clone());
    }
  };

  template <typename C>
  struct IteratorToObjectConverter<edm::RefVector<C> > {
    typedef edm::Ref<C> value_type;
    template <typename I>
    static value_type convert(const I &i) {
      return value_type(*i);
    }
  };

  template <typename T>
  struct IteratorToObjectConverter<edm::RefToBaseVector<T> > {
    typedef edm::RefToBase<T> value_type;
    template <typename I>
    static value_type convert(const I &i) {
      return value_type(*i);
    }
  };

  template <typename T>
  struct IteratorToObjectConverter<edm::PtrVector<T> > {
    typedef edm::Ptr<T> value_type;
    template <typename I>
    static value_type convert(const I &i) {
      return value_type(*i);
    }
  };

  template <typename OutputCollection, typename ClonePolicy = IteratorToObjectConverter<OutputCollection> >
  struct CollectionStoreManager {
    typedef OutputCollection collection;
    template <typename C>
    CollectionStoreManager(const edm::Handle<C> &h) : selected_(new OutputCollection) {}
    template <typename I>
    void cloneAndStore(const I &begin, const I &end, edm::Event &) {
      using namespace std;
      for (I i = begin; i != end; ++i) {
        typename ClonePolicy::value_type v = ClonePolicy::convert(i);
        selected_->push_back(std::move(v));
      }
    }
    edm::OrphanHandle<collection> put(edm::Event &evt) { return evt.put(std::move(selected_)); }
    size_t size() const { return selected_->size(); }

  private:
    std::unique_ptr<collection> selected_;
  };

  template <typename OutputCollection, typename EdmFilter>
  struct ObjectSelectorBase : public EdmFilter {
    ObjectSelectorBase(const edm::ParameterSet &) { this->template produces<OutputCollection>(); }
  };

  template <typename OutputCollection, typename EdmFilter>
  struct StoreManagerTrait {
    using type = CollectionStoreManager<OutputCollection>;
    using base = ObjectSelectorBase<OutputCollection, EdmFilter>;
  };

}  // namespace helper

#endif